The health of Europe’s forests is facing a quiet crisis, as the loss of mature trees – those with natural cavities – threatens a wide range of species dependent on them for survival. From woodpeckers and owls to bats and insects, these “den trees” provide crucial nesting and shelter opportunities. While conservation efforts often focus on planting new trees, experts are increasingly emphasizing the importance of preserving older growth and restoring traditional forest management practices that encourage the development of these vital habitats. The issue recently gained attention as vintners in the Czech Republic began installing artificial nesting boxes for the European roller (a bird known locally as ‘dudek’), a species that has declined sharply as diverse landscapes offer way to monoculture, including vineyards.
The decline in den trees isn’t simply a matter of deforestation. Modern forestry practices, prioritizing timber production, have historically favored uniform stands of trees, removing older, decaying trees that are essential for biodiversity. “I understand the well-intentioned efforts of all landowners and nature lovers to create artificial nesting conditions, and not just for rollers,” says Jiří Kmet, head of the Department of the Protected Landscape Area of Pálava, in the Czech Republic. “But this method is not a panacea. We must primarily plant trees and leave the vintage ones in the landscape.” The situation highlights a growing recognition that simply increasing tree numbers isn’t enough. the quality and age structure of forests are equally critical.
The Legacy of ‘Parezení’: Traditional Forest Management
Historically, a forest management technique known as “parezení” – a method of selective felling – played a vital role in maintaining a supply of den trees. This practice involved harvesting trees while allowing new shoots to sprout from the stump, ensuring continuous regeneration without clear-cutting. “When you come to such a forest after ten years, the shoots will have regrown, and they will be used for heating, which is technologically much simpler than felling large trees, and the stump continues to regenerate,” explains Pavel Dedek, an entomologist at the Pálava Protected Landscape Area. “The fact that it is pruned speeds up the formation of cavities, similar to the weeping willows we know from the paintings of Josef Lada.” This process created trees with numerous low-level cavities, providing ideal nesting sites for a variety of species.
Foto: Pavel Dedek, CHKO Pálava
Obrůstající pařez z Pálavy
However, this traditional approach largely disappeared as forestry practices shifted towards maximizing timber yield. “Today, forests are denser, trees are straight, they do not create cavities, but provide higher quality wood,” Dedek notes. “However, This represents not ideal for biodiversity.” The result is a landscape increasingly lacking in the structural complexity needed to support a diverse range of species. The Pálava region of the Czech Republic remains an exception, retaining a significant number of old-growth trees due to its historical land management practices. According to Dedek, the area continued to practice parezení until after World War II, later than many other regions which abandoned the method in the mid-19th century.
Pálava: A Model for Conservation
The Pálava Protected Landscape Area, located in South Moravia, offers a compelling example of how preserving older trees can benefit biodiversity. The region’s unique landscape, characterized by a mosaic of small fields bordered by trees, has helped maintain a higher density of den trees compared to areas with more intensive agriculture. “When we look at aerial photographs from 1938, we see small fields and trees on their borders,” Kmet explains. “There were many more trees in the landscape than You’ll see today. That is why we are planting avenues and trying to divide large soil blocks with field paths. But the main thing is to motivate owners to start planting trees on their land. Even if it is a long-distance run.”
Maintaining den trees presents challenges for various stakeholders, including road maintenance crews and those responsible for public green spaces. Concerns about safety often lead to the removal of older, potentially unstable trees. However, Kmet emphasizes that solutions exist, such as crown reduction and weight redistribution, to mitigate risks without necessarily removing the tree entirely. “Even if such a tree is not aesthetically valuable, it still plays a huge role in maintaining the species diversity of the area. It hosts not only large vertebrates and cavity nesters, such as the roller, but also many species of wood-decaying insects or bats. It simply makes sense.”
The Wider Implications for European Forests
The situation in the Czech Republic reflects a broader trend across Europe. Intensive forestry practices have led to a decline in the availability of deadwood and older trees, impacting a wide range of species. The European roller, a brightly colored bird that relies on cavities for nesting, is a particularly vulnerable species, with populations declining across much of its range. Recent reports indicate that vintners are increasingly resorting to installing artificial nesting boxes to compensate for the lack of natural cavities in vineyards, which have become increasingly monocultural.
The preservation of den trees requires a shift in perspective, recognizing the ecological value of decay and imperfection. It demands collaboration between landowners, forest managers, local authorities, and conservation organizations. Promoting sustainable forestry practices, encouraging the retention of older trees, and restoring traditional methods like parezení are crucial steps towards creating more resilient and biodiverse forests. The long-term health of Europe’s forests, and the countless species that depend on them, hinges on a renewed appreciation for the importance of these often-overlooked ecological treasures.
Looking ahead, ongoing monitoring of den tree populations and the effectiveness of conservation efforts will be essential. Further research is needed to understand the specific habitat requirements of different species and to develop targeted management strategies. The Pálava region serves as a valuable case study, demonstrating that with careful planning and a commitment to preserving natural processes, it is possible to maintain a healthy and diverse forest ecosystem.
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